Safety device for manhole covers



Feb. 11, 1936. c. E. REGO SA FETY DEVICE FOR MANHOLE CQVERS- Filed Sgapt. 27, 1935- Inventor: anarlcsl'flzgo, I

' b ma/zmm.

Patented Feb. 11 1936 UNITED STATES PATENT OFFICE 5 Claims.

This invention relates to safety devices for manhole covers and particularly for the covers of street manholes in which gases are liable to accumulate and cause an explosion whenever an elec- 5 trio current therein becomes short circuited, the principal object of the present invention being to provide a means for designating in a service station the particular manhole or manholes in which an explosion has occurred.

This object is attained by the mechanism illustrated in the accompanying drawing.

For the purposes of illustrating the invention, one preferred form thereof is illustrated in the drawing, this form having been found to give satisfactory and reliable results, although it is to be understood that the various instrumentalities of which the invention consists can be variously arranged and organized, and the invention is not limited to the precise arrangement and organize- 9 tion of these instrumentalities as herein shown and described except as required by the scope of the appended claims.

Of the drawing Figure 1 represents a plan of a manhole seat 5 and cover therefor.

Figure 2 represents a vertical section of same on line 2,2, on Fig. 1, drawn to an enlarged scale and showing associated therewith a diagram including other manholes, all electrically connected p to an annunciator in a service station.

Figure 3 represents an elevation of the casing of a circuit closer, and

Figure 4 represents a vertical section of same on line 4, 4, on Fig. 3.

; Similar characters indicate like parts throughout the several figures of the drawing.

In the drawing, l0 represents an annular seat having a depression H therein to receive a manhole cover l2.

\ The cover I2 is adapted to close a manhole l3 which has recesses l4 formed in the side wall thereof.

In each one of these recesses I4 is disposed a tubular member IS, the upper end of which is secured to the annular seat It].

Each tubular member I5 has a partition l6 therein and the lower end of each tubular member I 5 is provided with a closure I'I.

Above the closure l1 and below the partition I6 is a piston "3 adapted to reciprocate endwise of said tubular member l5.

Between the partition l6 and piston I8 is a helical spring l9 and just beneath each partition "5 is a filling plug 20.

By removing this filling plug 20 the space hetweenthe partition l6 and piston l8 may be filled with alemite or some'similar lubricant, this lubricant keeping the spring is and piston It in work: able condition at all times.

The piston 18 is threaded to the lower end of a 5 rod 2| extending upwardly through the partition l6 and having at its upper end a headed nut 22 extending through the cover I2, the head of each nut 22 being disposed in a depression I21: in saidcover. 10

The piston It may be adjusted lengthwise of the rod 21 to vary the tension of the spring l9 and then looked in adjusted position by means of the nuts 23, 24.

The closure I1 may be adjusted to vary the downward movement of the rod 21 Surrounding each tubular member ii are a plurality of anchors 25 extending outwardly between the bricks forming the walls of the manhole, thereby preventing any upward movement of the tubular member I5, these tubular members l5 having been disposed within the recesses I4 formed in the wall of the manhole.

The recesses l4 are closed by concrete I41: leaving the cylindrical wall to the manhole free from all protuberances extending into the manhole.

This is of some advantage as it prevents any injury to the workmen within the manhole.

One of the tubular members I5 is provided with a switch 26 which may be of any well known construction and includes a. movable member 21 in the path of a member 28 secured to the rod 2|.

This switch 26 is in an electric circuit 261: provided with a battery 29 and has a signal such as a lamp 30 in the circuit. 85

Other manholes I3a, I 3b, I3c, l3d, l3e, are connected by electric circuits 26a, 26b, 26c, 26d, 26c, to the battery 29 and in these circuits 26a, 26b, 26c, 26d, 26e, are lamps 30a, 30b, 30c, 30d, 30c, all a part of the annunciator 3|. 0

Whenever a switch 26 of either of these circuits 26a, 26b, 26c, 26d, 26c, is closed, a lamp 30a, 30b, 30c, 30d, 30c, will be illuminated and warn attendants in the service station an explosion has occurred in a particular manhole.

The movable member 21 of each switch 26 is pivoted at 21a and extends outwardly through a slot 2'"; of the casing of the switch 26, fitting said slot with sufficient friction to prevent its accidental movement.

This member 21 is connected to one end of the circuit wire 26:: while the other end of the service wire 26:: extends to a blade 210.

The movable member 21 is normally in the P sition shown in Fig. 4 of the drawing, but when 5| an explosion occurs and the cover I2 is lifted, the member 28 will come into contact with the cam surface of the member 21 and move it about its pivot 21a so that its side face will come into frictional contact with the blade 21c, the friction between the two siu'faces being sufficient to retain the member 21 in contact with said blade 210 until forced outwardly into its original position by one of the service men after the repairs have been made.

This can be done by inserting any small object through the hole 21d and moving the member 21 outwardly about its pivot.

When an explosion takes place within either manhole, its cover l2 will be raised from its seat 10 a limited distance, the springs l9 being compressed during this upward movement of the cover l2.

During the lifting of the cover the gas within the manhole will escape and then the springs l9 will return the cover l2 to its normal position.

During the lifting of the cover l2 the member 28 will operate the movable member 21 of a switch 26 and close its electric circuit to the particular signal lamp associated therewith,

The lamps may be located at any convenient point as in a service station.

Preferably the lamps are a part of an annunciator 3| and each lamp on the annunciator is electrically connected with a ,diflerent manhole safety device.

By means of this construction'whenever an explosion occurs in any particular manhole, a warning is given in the service station and the particular manhole in which the explosion occurs is indicated on the annunciator 3 I.

By this system the service station is warned whenever an explosion occurs and identification is made as to the particular point where the trouble occurs.

By use of this system the service man can quickly get to the point where the trouble has occurred and make the necessary repairs.

- When access is desired to the interior of the manhole, the headed nuts 22 threaded to the upper ends of the rods 2| may be removed and the cover l2 displaced from its seat Ill.

The cover J! has laterally extending projections 32 which restin recesses 33 in the seat Ill and when these projections 32 are positioned within the recesses 33 the nuts 22 will always be in register with the rods 2| within the tubular members IS.

The switch 26 is so constructed that, when once closed by the upward movement of the disk 28, it will remain closed until the service men reach the manhole l3 and make the necessary repairs, it being then returned to its normal position by one of said service men.

It is believed the operation and many advantages of the invention will be understood readily without further description.

Having thus described my invention, I claim:

1. In combination with an unobstructed manhole located below .the surface of a street or the like and in which a man may work; a cover therefor having a level upper face alined with said street surface; an annular seat for said cover; a rod depending. from said cover; a piston thereon; a housing for said piston outside the wall of said manhole; a spring coacting with said piston to retain said cover on its seat; an electric circuit; a normally open switch therefor in the wall of said housing; and means on said rod for closing said switch whenever said piston is raised against the tension of said spring.

2. In combination with an unobstructed manhole below the surface of a. street or the like and in which a man may work; a manhole cover therefor having a level upper face alined with said street surface and adapted to have only a slight upward movement when an explosion occurs in said manhole; a member secured to and depending from said cover; a normally open switch; means forming an electric circuit including said switch; and means on said member for closing saidswitch during the upward movement of said member.

3. In combination with an unobstructed manhole below the surface of a street or the like and in which a man may work; a manhole cover therefor having a level upper face alined with said street surface; means for limiting the upward movement of said cover when an explosion occurs in said manhole; an annular seat for said cover; a tubular member depending from said seat; a rod depending from said cover into said tubular member and movable with said cover; a switch actuating block secured to and movable with said rod; means forming an electric circuit for said manhole; and a normally open switch in said circuit positioned in the wall of said tubular member above and extending into the path of movement of said block.

4. In combination with an unobstructed manhole below the surface of a street or the like and in which a man may work; a manhole cover therefor having a level upper face alined with said street surface; means for limiting the upward movement of said cover when an explosion occurs in said manhole; an annular seat for said cover, said cover and seat having alined holes therein; a shouldered nut in said holes; a rod threaded at its upper end to said nut and depending from said cover; a normally open switch; means forming an electric circuit including said switch; and means on said rod for closing said switch during the upward movement of said rod,

5. In combination with an unobstructed manhole below the surface of a street or the like and in which a man may work; a manhole cover therefor having a level upper face alined with said street surface; an annular seat for said cover; a tubular member depending from said seat and having an oil chamber in its lowest end; a rod depending from said cover and extending into said oil chamber; a piston in said chamber secured to said rod and coacting with the oil in said chamber to permit only a slight upward movement to said cover when an explosion occurs in said manhole; a spring between said piston and the upper wall of said chamber for normally retaining said cover on its seat; a switch-actuating block secured to and movable with said rod; means forming an electric circuit for said manhole; and a normally open switch in said circuit positioned in the wall of said tubular member above and extending into the path of movement of said block.

CEARLIS I. R160. 

